Thermal management methods

ABSTRACT

A thermal management system for a vehicle includes a heat exchanger having a thermal energy storage material provided therein, a first coolant loop thermally coupled to an electrochemical storage device located within the first coolant loop and to the heat exchanger, and a second coolant loop thermally coupled to the heat exchanger. The first and second coolant loops are configured to carry distinct thermal energy transfer media. The thermal management system also includes an interface configured to facilitate transfer of heat generated by an internal combustion engine to the heat exchanger via the second coolant loop in order to selectively deliver the heat to the electrochemical storage device. Thermal management methods are also provided.

GOVERNMENT RIGHTS

The United States Government has certain rights in this inventionpursuant to Contract No. DE-AC07-99ID13727, and Contract No.DE-AC07-05ID14517 between the United States Department of Energy andBattelle Energy Alliance, LLC.

TECHNICAL FIELD

Aspects of the invention generally relate to thermal management systems(TMSs) and methods.

BACKGROUND OF THE INVENTION

Hybrid electric vehicles (HEVs) and electric vehicles (EVs) provideimproved fuel economy and reduced air emissions over conventionalvehicles. The performance of HEVs and EVs depend on energy storagesystems such as batteries. Battery performance influences, for example,acceleration, fuel economy, and charge acceptance during recovery fromregenerative braking. As the cost of the batteries, durability, andlife-cycle affect the cost and reliability of a vehicle using thebatteries for vehicular operation, parameters that affect the efficiencyof the batteries may have to be optimized to achieve optimized vehicularperformance.

It is known that temperature has an influence over battery performance.Battery modules carrying batteries are preferred to operate within anoptimum temperature range that is suitable for a particularelectrochemical pair. For example, the desired operating temperature fora lead acid battery is 25° C. to 45° C. Battery modules may also have tobe operated at uniform temperatures as uneven temperature distributionmay result in varied charge-discharge behavior. Such variedcharge-discharge behavior may lead to electrically unbalanced modulesand reduced battery performance.

HEVs may be less reliable in northern latitudes due to cold temperatureconstraints imposed on the batteries carried by the HEVs. Lithium ionbatteries have been a candidate for use in HEVs, and such batteries haveoptimum performance when operating from 0-40° C. Below 0° C., poweroutput of the batteries diminishes and the effect of temperature becomesmore severe as the level of discharge increases. Conversely, astemperatures exceed above 40° C., detrimental cathode corrosion andother irreversible reactions may occur resulting in shortened batterylife.

Accordingly, a battery thermal management system (TMS) is needed toachieve desired and reliable performance in varied climatic conditionswhile minimizing temperature excursions outside a desired temperaturerange.

SUMMARY OF THE INVENTION

Aspects of the invention also relate to a comprehensive thermalmanagement system for hybrid electric vehicles which include both aninternal combustion engine and battery based locomotion (example,lithium-ion, or nickel metal hydride). Aspects of the invention alsodisclose a thermal management system configured to provide a mechanismto pre-warm a vehicle's battery module, having a plurality of individualcells, in cold conditions, provide auxiliary warmth to the module asneeded, and remove heat from it as the batteries heat up due to normalohmic discharge and recharge.

In some embodiments, a thermal management system for a vehicle includesa heat exchanger having a thermal energy storage material providedtherein. The thermal management system includes a first coolant loopthermally coupled to an electrochemical storage device located withinthe first coolant loop and to the heat exchanger, a second coolant loop,thermally coupled to the heat exchanger, the first and second loopsconfigured to carry distinct thermal energy transfer media. The thermalmanagement system also includes an interface configured to facilitatetransfer of heat generated by an internal combustion engine to the heatexchanger via the second coolant loop in order to selectively deliverthe heat to the electrochemical storage device. Thermal managementmethods are also provided.

In other embodiments, a thermal management system for a hybrid electricvehicle includes a heat exchanger having a phase change materialprovided therein, a first fluid loop having a first coolant mixtureflowing therein, and a second fluid loop having a second coolant mixtureflowing therein, the second coolant mixture being distinct from thefirst coolant mixture. The first and second fluid loops are configuredto be in thermal communication with the heat exchanger, the heatexchanger being configured to flow only the first coolant mixture withinthe heat exchanger. The thermal management system also includes athermal interface configured to transfer heat produced by an internalcombustion engine of the vehicle to the heat exchanger, the heatexchanger being configured to store the heat generated by the internalcombustion engine and selectively provide the stored heat to controlthermal characteristics of various components of the vehicle includingthe battery module.

In yet other embodiments, a thermal management method for a vehicleincludes providing a heat exchanger having a thermal energy storagematerial disposed therein, providing first and second coolant loops tocirculate distinct coolant mixtures through the respective first andsecond coolant loops, thermally coupling the first coolant loop to abattery module located within the first coolant loop, thermally couplingthe second coolant loop to the heat exchanger, and providing aninterface in close proximity to the second coolant loop. The interfaceis configured to transfer heat generated by an internal combustionengine of the vehicle to the heat exchanger, via the second coolantloop, for storage within the thermal energy storage material. The methodalso includes selectively performing one or more of preheating thebattery module, heating a passenger cabin of the vehicle, increasingsensible heat or latent heat of fusion of the material from a firstthermal state to a higher second thermal state using the heat storedwithin the thermal energy storage material.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 shows a schematic of a vehicle in accordance with variousembodiments of the invention.

FIG. 2 is a schematic of a thermal management system as shown in FIG. 1in accordance with various embodiments of the invention.

FIG. 3A is a schematic of a heat exchanger shown in FIG. 2 in accordancewith some embodiments of the invention.

FIG. 3B is a schematic of a heat exchanger shown in FIG. 2 in accordancewith other embodiments of the invention.

FIG. 4 is a graph illustrating a thermal cycle for a phase changematerial that is stored in a heat exchanger in accordance with variousembodiments of the invention.

FIG. 5 is a graph illustrating temperature history of a phase changematerial and battery cooling fluid in accordance with variousembodiments of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

The following terminology as described below is used to define termsthat are used in this application.

The following operational parameters and control strategy may be used invarious embodiments:

Measured Temperatures.

-   T_(Batt): average or representative temperature within battery    module of battery 10.-   T_(Cab): representative temperature of coolant within the internal    combustion engine cabin (ICE cabin) heater core 1 18.-   T_(PCM): average or representative temperature within phase change    material (PCM) module 214, 218 of heat exchanger (HX) 116.-   T_(Rad): representative temperature of the internal combustion    engine radiator coolant/fluid in loop 104.

Set-point Temperatures.

-   T_(min): minimum desirable battery temperature.-   T_(max): maximum desirable battery temperature.-   T*: minimum desirable temperature of cabin heater core.-   T**: phase change material melting temperature plus a margin of 5 to    10° C.

Control strategy in accordance with various embodiments of theinvention.

-   V1—full open to heat exchanger 106: T_(Batt)>T_(max); otherwise    closed to heat exchanger 106.-   V2—full open to Bypass: T_(Batt)>T_(max); otherwise closed to    Bypass.-   V3—full open to cabin core: [(T_(Batt)>T_(min)) and    (T_(Batt)<T_(max))] and (T_(Cab)<T*) and (T_(Rad)<T*) and    (T_(PCM)>T_(Cab)); otherwise open to internal combustion engine    radiator 120.-   FAN 108—On at T_(Batt)>T_(max); otherwise Off.-   P1—On: (T_(Batt)<T_(min)) or (T_(Batt)>T_(max)).

Off: (T_(Batt)>T_(min)) and (T_(Batt)<T_(max)).

-   P2—On: (a) using internal combustion engine coolant/fluid in loop    104 to help warm batteries 110    -   (T_(Batt)<T_(min)) and (T_(PCM)<T_(min)) and (T_(Rad)>T_(PCM)).    -   (b) sending excess heat to cabin heater core 118        [(T_(Batt)>T_(min))] and (T_(Batt)<T_(max)) and        (T_(PCM)>T_(Cab)) and (T_(Cab)<T*) and (T_(Rad)<T*).    -   (c) remelting phase change material (214, 218) and increasing        sensible heat of the phase change material (214, 218)-   {[(T_(Batt)>T_(min)) and (T_(Batt)<T_(max))] or (T_(Batt)>T_(max))}    and (T_(PCM)<T**) and (T_(Rad)>T**).

Otherwise Off.

FIG. 1 shows a vehicle 10 embodying the invention. The vehicle 10includes a thermal management system 100 and an on-board processor (andmemory) or processor 101 in communication with the thermal managementsystem 100.

The thermal management system 100 is configured to manage heat (e.g.,thermal management of electrochemical energy storage device 110 (e.g.,battery module or battery)) (FIG. 2) of vehicle 10 during various phasesof vehicular operation, such as for example, cold-start conditions,normal conditions, and hot environmental conditions. The device 110 isgenerally referred to herein as battery 110. The device 110 may also beprovided as an electrochemical energy storage device module. Furtherdetails of the thermal management system 100 are set forth and describedbelow with reference to FIG. 2. Exemplary embodiments of battery typesinclude lithium-ion, nickel-metal-hydride, and lead-acid. Theelectrochemical energy storage device may comprise one or morebatteries, capacitors, fuel cells, or combinations thereof.

The on-board processor 101 is configured to control various operationsof the vehicle 10 including controlling of various sensors (not shown)of the vehicle 10. The on-board processor 101 may also be configured tocontrol heat (e.g., heat supplied/discharged to/from the battery 110(FIG. 2)) together with the thermal management system 100, duringvarious phases of vehicular operation as noted above. In someembodiments, the processor 101 may comprise circuitry configured toexecute provided programming. For example, the processor 101 may beimplemented as a microprocessor or other structure configured to executeexecutable instructions of programming including, for example, softwareor firmware instructions. Other exemplary embodiments of the processor101 include hardware logic, PGA, FPGA, ASIC, or other structures. Theseexamples of the processor 101 are illustrative. As such, otherconfigurations are possible for implementing operations performed by theprocessor 101.

In some embodiments, a separate processor is used in connection with thethermal management system 100 than the on-board processor.

In other embodiments, the processor 101 may be programmed withpredetermined temperature value(s) in a desired temperature range (e.g.,of battery 110 (FIG. 2)) corresponding to various phases of vehicularoperation as noted above. The processor 101 is configured to compare thestored value(s) with measured temperature value(s) and provideinstructions, based on the comparison, to the thermal management system100 configured to manage heat of the battery 110 during various phasesof operation of the vehicle 10. Further details of such heat managementare set forth below with reference to FIG. 2.

FIG. 2 is a schematic of the thermal management system 100 as shown inFIG. 1. The thermal management system 100 includes heat exchanging fluidloops 102, 104, heat exchangers 106, 116, a fan 108 corresponding to theheat exchanger 106, a battery 110 (e.g., a lithium-ion battery orbattery bank), a coolant expansion tank (ET) 112, pumps P1 and P2, abypass loop 114, an internal combustion engine cabin heater core 118(referred to herein as internal combustion engine cabin), an internalcombustion engine radiator 120, and an interface 122. The thermalmanagement system 100 also includes a plurality of valves V1-V7 (e.g.,control valves V1-V3 and check valves V4-V7).

The loop 102 (shown to the left of heat exchanger 116) is configured asa battery side coolant loop for flowing or recirculating coolant or afluid or a thermal energy transfer medium from the expansion tank 112 toadd or remove heat from the battery 110 of the vehicle 10. The loop 102is alternatively referred to herein as “battery fluid loop” . In someembodiments, coolant flowing in the loop 102 is circulated via the loop114 bypassing the heat exchanger 116. In other embodiments, coolantflowing in the loop 102 flows through the heat exchanger 116 withoutflowing via the loop 114. The control valve V2 is appropriatelycontrolled (e.g., opened or closed) to achieve such functionality.

The loop 104 (shown to the right side of heat exchanger 116) isconfigured as an internal combustion engine side coolant loop 104 forflowing or recirculating heat exchanging fluid or a coolant via the heatexchanger 116, the internal combustion engine cabin 118 in someembodiments. In other embodiments, the loop 104 is configured forflowing or recirculating the heat exchanging fluid via the heatexchanger 116 and the internal combustion engine radiator 120 bypassingthe internal combustion engine cabin 118. The heat exchanging fluidflowing through the loop 104 may be a coolant used for cooling theinternal combustion engine (not shown), whereas the fluid flowingthrough the loop 102 can be of a different composition, compared to thefluid in the loop 104, to achieve unique heat transfer performance forthe loop 102.

The heat exchanger 106 together with the fan 108 is configured tocontrol temperature of the battery 110 to be within a predeterminedoptimal range. In one embodiment, fluid in the loop 102 is recirculatedthrough the heat exchanger 106 in order to control excessivetemperatures of the fluid in the loop 102, the fluid being circulatedthrough the battery 110.

Battery 110 includes energy storage batteries configured to provideenergy for operation of the vehicle 10. The battery 110 may beconfigured to have the loop 102 passing through the battery 110 tocontrol thermal characteristics of the battery 110. It will beappreciated that the battery 110 may be configured to include a moduleto house a fluid (e.g., coolant) and such module may be configured to becoupled to the loop 102.

The expansion tank 112 may be configured as a coolant expansion tank forhousing the fluid that is circulated in the loop 102.

The loop 114 is configured as a bypass loop for the fluid recirculatingin the loop 102. Fluid in the loop 102 may be flowed through the loop114 bypassing the heat exchanger 116 in some embodiments.

The heat exchanger 116 is configured as a well-insulated heat exchangervessel to store a fixed volume of phase change material (referencenumerals 214, 218 of FIGS. 3A, 3B) and a small volume of fluid (e.g.,coolant) that is pre-warmed from a prior operation of the vehicle 10.The phase change material of the heat exchanger 116 provides latent andsensible heat that may be transferred to the fluid flowing through theheat exchanger 116 in some embodiments.

The heat exchanger 116 is further configured to facilitate heat transferto control thermal characteristics of the battery 110 as well ascontrolling a temperature of a passenger cabin of the vehicle 10 byflowing the fluid in the loop 104 via the internal combustion enginecabin 118 in some embodiments. Further design details of the heatexchanger 116 are set forth below with reference to FIGS. 3A-3B.

The internal combustion engine cabin heater core 118 is configured toprovide heat to the passenger cabin of the vehicle 10 to maintain atemperature of the passenger cabin within a predetermined temperaturerange.

The internal combustion engine radiator 120 is configured to control thetemperature of the internal combustion engine.

The interface 122 is configured as an interface between the thermalmanagement system 100 and the internal combustion engine (not shown) ofthe vehicle 10. For example, the interface 122 is designed to transportheat transfer fluids containing waste heat generated by the internalcombustion engine to control the temperature of the battery 110 providedin the loop 102. Waste heat generated by the internal combustion enginemay be transferred to the heat exchanger 116 via the loop 104, and theheat transferred to the heat exchanger 116 is stored in the phase changematerial resident in the heat exchanger 116. Such heat stored in thephase change material resident in the heat exchanger 116 is thenprovided to the battery 110 via the loop 102 to increase the temperatureT_(Batt) of the battery 110.

Phase change materials are desirable in a thermal management system dueto exothermic heat of phase change, or latent heat, that is released asthe phase change material undergoes a transition from one state (e.g.,liquid) to another state (e.g., solid). Phase change materials are alsodesirable as a thermal cycle of most phase change materials isreversible, thus enabling the phase change material to be regeneratedfrom a solid state to a liquid state by the addition of external heat.With regeneration, a phase change material may be used as a reliableheat source for multiple times. The combination of the phase changematerial latent heat and sensible heat (e.g., heat above that which isrequired to achieve phase change material melting) increases the overallheating value per mass.

The phase change materials used in various embodiments of the inventionare desired to have the following characteristics:

(i) Undergo fusion/melting within the desired temperature range (e.g.,melting below 90 degrees C. and fusion (crystallization) at no lowerthan −20 degrees C.);

(ii) limited or controlled supercooling so that nucleation would occuron demand;

(iii) high heat of fusion;

(iv) rapid crystallization so that heat is generated at a useable rate;

(v) ability to undergo numerous cycles without degradation or diminishedperformance;

(vi) be inexpensive, readily available, non-toxic, non-flammable,non-reactive, and non-corrosive.

The inventors have determined the materials as listed in Table I to beviable phase change material candidates for various embodiments of theinvention.

TABLE I Melting Autonucleation Phase Change Material Temperature, ° C.Temperature, ° C. Sodium acetate 3.6-hydrate 58 −10 to −18 Sodiumacetate 4.0-hydrate 58 −14 to −18 Sodium acetate/magnesium 58 −17 to −21acetate (1 wt % Mg) 3.5-hydrate Sodium acetate/magnesium 58 −14 to −20acetate (5 wt % Mg) 3.5-hydrate Ethylene carbonate 36 8.2 Ethylenecarbonate/propylene 36 −0.5 carbonate (3.7 mole % PC) Ethylenecarbonate/propylene 36 3.4 carbonate (5.6 mole % PC) Ethylenecarbonate/propylene 36 12.8 carbonate (6.7 mole % PC) Calcium chloride6.0-hydrate 30 2 Sodium hydrogen phosphate 12- 35 20 to 25 hydrate(ambient)

In accordance with various embodiments, the thermal management system100 is configured to maintain temperatures of the battery 110 within anoptimal range while providing heat for cabin comforts under coldenvironmental conditions. For example, an optimal range may be chosen tobe between 0-40 degrees Centigrade. Such a temperature range was foundto be favorable for Lithium-ion batteries.

During the operation of the thermal management system 100, fluids withinthe loops 102, 104 are circulated to add or remove heat according to apredetermined thermal protocol (e.g., predetermined values orestablished conditions) of the vehicle 10. Valves V1-V3 (e.g., controlvalves) and valves V4-V7 (e.g., one-way check valves) are configured toensure that respective fluids in the loops 102, 104 flow through desiredfluid paths. Valves VI and V2 are specified as thermostatic, whereintheir actuation is driven by the temperature of the fluid flowingthrough each. Valve V3 is electronically actuated based on control logicresident within the processor 101 and relevant temperature inputsdescribed herein. The operation of the thermal management system 100 maybe described by the following exemplary modes of operation: (1)cold-start conditions, (2) normal conditions, (3) hot mode. Each mode ofoperation is controlled by defined control parameters as describedbelow.

Under cold-start conditions, the temperature (T_(Batt)) of the battery110 may not be within a predetermined temperature range. In someembodiments, if T_(Batt) is beneath the predetermined temperature range,then the pump P1 is operated (e.g., turned ON) and valve V2 iscontrolled to circulate the fluid (e.g., coolant) from the battery 110to the heat exchanger 116, whereupon sensible heat (e.g., heat stored inthe fluid present in the heat exchanger 116) is transferred to the fluidcirculating in the loop 102 and flowing through the heat exchanger 116.For example, after pump P1 is operated, fluid from the battery 110 andflowing in the loop 102 flows to the heat exchanger 116 and displacesthe pre-warmed fluid therein. The pre-warmed fluid is circulated to thebattery 110 by appropriately operating the valves V4 and V1. In otherembodiments, latent heat from the phase change material resident in theheat exchanger 116 can also be transferred if the fluid circulating inthe loop 102 and in contact with the phase change material (referencenumerals 214, 218 of FIGS. 3A, 3B) in the heat exchanger 116 issufficiently cold to initiate autonucleation of the phase changematerial 214, 218.

However, if the heat exchanger 116 is unable to provide sufficient heat(e.g., to the fluid circulating in the loop 102 through the heatexchanger 116) to increase T_(Batt) due to the low temperature T_(PCM)of the phase change material (214, 218), then pump P2 is operated (e.g.,turned ON) to circulate fluid (e.g., internal combustion engine coolant)from the internal combustion engine (not shown) to the heat exchanger116 via the interface 122 (e.g., internal combustion engine-heatexchanger interface). In this case, waste heat generated by the internalcombustion engine is transferred to the heat exchanger 116. For example,if the fluid in the internal combustion engine is warmer than T_(PCM)and { (T_(Batt)<T_(min)) and (T_(PCM)<T_(min))}, then the pump P2 isturned ON to circulate warm fluid from the internal combustion engine tothe heat exchanger 116 via the interface 122. After the pump P2 isturned ON, the pump P1 is operated to circulate fluid, present in theloop 102, through the heat exchanger 116 until the temperature of thebattery 110 is restored to be within the predetermined temperaturerange.

Operation of thermal management system 100 under normal conditions isnow described. Normal conditions described herein are defined by thetemperature T_(Batt) of the battery 110 being within the predeterminedtemperature range. Under the normal conditions, the pump P1 remains OFF.However, the pump P2 may recirculate fluid in the loop 104 to the heatexchanger 116 in order to remove excess heat from the heat exchanger 116if the temperature (T_(PCM)) of the phase change material (214, 216)resident in the heat exchanger 116 is greater than the temperature ofthe fluid circulating in the loop 104. After the excess heat from thephase change material (214, 216) is transferred to the fluid in the loop104, valves V5 and V3 are appropriately controlled to route the fluidfrom the heat exchanger 116, with the received excess heat, to theinternal combustion engine cabin 118 if the temperature of the internalcombustion engine cabin 118 is less than a predetermined temperaturerange.

However, if the temperature of the internal combustion engine cabin 118is within a predetermined temperature range, then valve V3 is controlledto route the fluid from the heat exchanger 116, with the received excessheat, to the internal combustion engine radiator 120 and bypassing theinternal combustion engine cabin 118. Circulating the fluid that isreceived from the heat exchanger 116 to flow through the internalcombustion engine radiator 120 further increases the temperature of thefluid that is circulated in the loop 104. The fluid flowing from theinternal combustion engine radiator and circulating in the loop 104 isflowed through the heat exchanger 116, by controlling the valve V7 andthe pump P2, to remelt the phase change material (214, 218) resident inthe heat exchanger 116, thereby increasing the thermal energy of thephase change material. This process ensures that the phase changematerial is remelted at the first opportunity, thereby reactivating thephase change material and keeping it ready for subsequent use undercold-start conditions as explained above.

It will be appreciated that normal conditions may occur under coldambient conditions since the battery 110 and the heat exchanger 116 aresufficiently insulated to render the thermal management system 100operable within predetermined optimal temperature ranges. The types andmethods of insulation used may depend on maximum acceptable heat lossrates for the battery 110 and the heat exchanger 116. Such heat lossrates may depend on vehicle-dependent factors as well as regionalweather characteristics. In some embodiments, the battery 110 and theheat exchanger 116 are designed such that T_(Batt) is above 0 degrees C.and T_(PCM) is above 40 degrees C. over a period of thirty-six hours ofinactivity of the vehicle 10.

Operation of the thermal management system 100 under hot conditions isnow described. Hot conditions occur when temperature (T_(Batt)) of thebattery 110 exceeds the optimal temperature range due to normal ohmicdischarge and recharging of the battery 110. Under hot conditions, fluidin the loop 102 is made to bypass the heat exchanger 116 by controlling(e.g., closing valve to heat exchanger 116 and opening valve to bypassloop 114) the valve V2. The valve V1 controls the fluid in the loop 102to flow through the heat exchanger 106 (e.g., air cooled heatexchanger). After receiving the fluid in the heat exchanger 106, the fan108 is turned ON until T_(Batt) drops below the maximum optimaltemperature (e.g., 40 degrees C.). Under the hot conditions, and in someembodiments, the pump P2 may be turned ON while the valve V3 isconfigured to direct the fluid in the loop 104 to circulate between theinternal combustion engine radiator 120 and the heat exchanger 116 toheat the phase change material (214, 218) resident in the heat exchanger116 as described above.

FIG. 3A is a cross-sectional schematic of the heat exchanger 116 shownin FIG. 2, in accordance with some embodiments. The heat exchanger 116includes the fluid circulation loops 102, 104, insulation 202, a fluid(e.g., coolant) filled chamber 204, a plurality of heat exchange fins208, heat exchange tubing 210, 211, a baffle member 212, and a phasechange material filled pouch 214.

The fluid circulation loops 102, 104 are configured to circulate fluidto control, for example, the thermal characteristics of the battery 110,temperature of the internal combustion engine cabin 118, and the heatcontent of the phase change material resident in the heat exchanger 116.Such have been described above with reference to FIG. 2 and thereforewill not be repeated.

The chamber 204 is configured to circulate fluids received from theloops 102, 104, respectively in order to control the temperature of thecirculating fluids to be within predetermined temperature ranges. Thefluid circulating in the loop 102 flows within the heat exchanger 116and the chamber 204 while fluid circulating in the loop 104 flowsthrough the tubing 211 without flowing through the chamber 204.

The heat exchange fins 208 and the heat exchange tubing 210, 211 may beprovided within the pouch 214 (e.g., heavy-gauge polymer pouch) filledwith phase change material. In one embodiment, the pouch 214 isconfigured to expand and contract as the phase change material disposedtherein undergoes changes in density during phase transitions. In oneembodiment, heat exchange tubing 210, 211 may share the heat exchangefins 208. As noted above, fluid circulating in the loop 104 and flowingvia the tubing 211 remains within the tubing 211 during its passagethrough the heat exchanger 116. However, fluid circulating in the loop102 and flowing via the tubing 210 passes from the tubing 210 into thechamber or void space 204 provided between the phase change materialpouch 214 and an internal wall bounded by the insulation 202 of the heatexchanger 116.

The baffle 212 blocks the pathway of the fluid circulating in the loop102, the tubing 210, and the chamber 204 such that the fluid is forcedto travel around the pouch 214 before it is allowed to leave the heatexchanger 116, thereby facilitating increased heat absorption by thephase change material resident in the heat exchanger 116.

The embodiment shown in FIG. 3A may be desired where heat transfer rateto and from the phase change material provided in the pouch 214 isdesired to be maintained at a predetermined level. Further, theembodiment shown in FIG. 3A may be used where an auxiliary device or anucleation triggering device (not shown) is desired to be placed inclose proximity with the phase change material filled pouch 214 topromote forced nucleation.

In another embodiment, a “nucleation triggering device” may be providedwithin the phase change material (PCM) reservoir in order to activatethe phase change material (e.g., 214, 218) on demand. This mode ofactivation may be provided as an alternative to autonucleation, and maybe performed per the control logic (e.g., processor 101) resident in thevehicle. Enabling the phase change material to be activated on demandprovides more consistent and timely nucleation of the phase changematerial. For example, the auxiliary device or nucleation triggeringdevice may be employed within the tubular encapsulated phase changematerial within heat exchanger 1116 (FIG. 3B). An exemplary embodimentof such triggering device is a fixed stainless steel disc (e.g., fixedwithin a short, rigid tubular enclosure) having a slight concavity, thathas several parallel thin slits cut into its interior. Upon flexure ofthe disc through a mechanical trigger, the interfacial dynamics betweenthe disc and liquid phase change material induce phase change materialcrystallization. The inventors have demonstrated and found to beeffective a device comprised solely of the stainless steel disc (havingexemplary dimensions of ⅝ inch diameter by 0.02 inch thickness) to beeffective for nucleating PCM materials such as sodium acetatetrihydrate, ethylene carbonate, and calcium chloride hexahydrate.Stainless steel nucleators having other designs are possible.

FIG. 3B is a cross-sectional schematic of the heat exchanger 116 inaccordance with some embodiments wherein elements like those shown inFIG. 3A are identified using similar reference numerals, but with aprefix “1” added.

In a preferred embodiment of the invention, the phase change material ofthe heat exchanger 1116 may be encapsulated in section(s) of flexibletubing instead of being encapsulated in spheres 218. The flexible tubingmay be configured to conform to the internal space of the heat exchanger1116 (e.g., coils, serpentine, or straight sections, etc.). Theinventors have discovered that by using the flexible tubing instead ofthe spheres, a lower volume of encapsulant material is used for asimilar volume of the phase change material. The ratio of encapsulantvolume to the volume of the phase change material may be further reducedby using the flexible tubing with a thinner wall thickness. Exemplaryselection criteria for the encapsulant tubing include high thermalconductivity, chemical compatibility, thermal compatibility,expandable/contractible properties of the tubing with phase changematerial phase changes, and increased lifetime. If wide variations ofphase change material density are anticipated, then ends of the tubingmay be heat-sealed or capped to allow a small volume of air to betrapped within the tubing.

The heat exchanger 1116 includes fluid circulation loops 1102 and 1104,an insulation 1202, a plurality of heat exchange fins 1208, a heatexchange tubing 1211, a baffled section 220 having phase change materialencapsulated in spheres 218. The encapsulating material may bepolypropylene in one case. In one embodiment, the baffled section 220with the phase change material spheres 218 is configured to surround thetubing 1211. Fluid in the circulation loop 1102 flows in the baffledpathway indicated by the arrows. The fluid in the loop 1102 is providedin intimate contact with the phase change material spheres 218. However,the fluid in the loop 1102 does not flow to disperse within the baffledsection 220.

The embodiment shown in FIG. 3B may be desired where the phase changematerial resident in the heat exchanger 1116 has an autonucleation pointwithin a predetermined temperature range (e.g., 0-40 degrees C.). Theheat exchanger 1116 shown in FIG. 3B may be easier to service, and isconfigured to use different phase change materials as the phase changematerial is encapsulated in spheres.

The embodiments of the heat exchanger shown in FIGS. 3A and 3B areexemplary. Other arrangements (e.g., a plate-and-frame design withexternal fins) of the heat exchanger are possible. An oval orcylindrical profile of the overall heat exchanger may be preferred forsome other vehicle applications. Performance of the heat exchanger(e.g., heat exchanger 116) may be optimized by using an intelligentselection of phase change materials, such as for example, organiccarbonates or hydrated inorganic salts shown in Table I as above. Thechoice of a phase change material may be based on the vehicle type andthe geographic region of the vehicle's intended use.

FIG. 4 is a graph illustrating a thermal cycle for a phase changematerial stored in a heat exchanger (e.g., heat exchanger 116) inaccordance with various embodiments of the invention. The thermal cyclepath A-B-C shown in the graph indicates a normal thermal cycle, whilethe path A-B′-C indicates a shortened thermal cycle resulting in anincomplete release of heat from the phase change material resident inthe heat exchanger 116. The general steps for the phase change materialutilization cycle in accordance with the various embodiments are shownin Table II as below:

TABLE II Temperature Step Change Description/Requirements 1. Activationat low At T_(a) May occur at any temperature lower than    ambienttemperature the melting point (T_(m)) but above the glass    (T_(a))transition temperature (T_(g)) of a metastable phase change material,provided the phase change material is in the liquid state. It ispreferred to activate the phase change material via intelligent control,e.g., do not want spontaneous uncontrolled activation. 2. Chain reactionfusion T_(a) to T_(f) Energy Release: exothermic transition   (exothermic) from liquid to solid proceeds along a thermal path that issystem dependent, accounting for the unique rate of heat release fromthe phase change material. The maximum fusion temperature (T_(f)) islower than the melting point as shown, and may vary according to theinitial state of the phase change material system, such as, for example,phase change material mass, phase change material conductivity,configuration, rate of heat transfer to the surroundings, etc. 3.Regeneration T_(f) to T_(m) Energy Uptake: heat absorption into phasechange material occurs as the material changes from a solid (ordered) toa liquid (random). Heat source would be waste heat (e.g., from internalcombustion engine coolant provided in loop 104 or battery-side coolantprovided in loop 102) at or above T_(m). Phase change material could beheated above the melt temperature to increase its sensible heat. Ifstored in a well-insulated vessel, the molten phase change material mayretain a high heating value. 4. phase change T_(m) to T_(a), but Phasechange material is allowed to cool    material is cooled by over T_(g)and reaches its autonucleation    contact with cold temperature,whereupon it undergoes    coolant under cold-start transition fromliquid state to solid state.    conditions Alternately, the PCM couldundergo forced nucleation while being at a temperature above itsautonucleation point, yet below its melting point.

FIG. 5 is a graph illustrating temperature history of a phase changematerial and the fluid (e.g., battery cooling fluid) circulating in theloop 102 in accordance with various embodiments of the invention. In thedescription of FIG. 5, references to PCM refer to the phase changematerial (e.g., 214, 218) resident in the heat exchanger 116 as setforth in various embodiments.

Initially, the phase change material may be in a liquid state and at ahigher temperature than the fluid circulating in the loop 102. Such astate is identified as “Regime 1” on the temperature-history graph ofFIG. 5. The phase change material would continue to transfer heat, witha loss in temperature, until crystallization occurs at a temperatureT_(autonuc). After nucleation begins, crystallization spreads throughoutthe phase change material and is accompanied by a rise in temperature.The ultimate temperature reached by the phase change material during thesecond regime (e.g., Regime 2) is its melting temperature. ThroughoutRegime 2, heat is transferred to the fluid in the loop 102. After thephase change material crystallization is complete, the phase changematerial present in a solid state is still warm relative to the fluidcirculating in the loop 102 and continues to deliver heat to such fluid.Such a state is identified by Regime 3. Regime 3 continues until thetemperature of the phase change material and the temperature of thefluid in circulating the loop 102 are equal.

During the course of normal vehicle use, battery 110 experiencesohmic-type heating as it is discharged and recharged. Excess heat fromthe battery 110 that is warmed may be transferred back to the phasechange material as shown in Regime 4. As noted above, the phase changematerial is selected to undergo phase transition over a desired range oftemperature. In Regime 4, transfer of heat from the loop 102 to thephase change material continues so long as the temperature of thebattery 110 is higher than the temperature of the phase change material.Continued heat transfer to the phase change material would result inmelting of the phase change material until the phase change material isin a completely liquid state (Regime 5). Additional heating of the phasechange material that is in the liquid state may be possible andidentified by Regime 6. The additional heat may be provided from warmbatteries (e.g., battery 110), or from an internal combustion engine asin the case of hybrid electric vehicles. At the conclusion of Regime 6,the phase change material is fully charged and ready for another cycleof operation.

The following equations estimate temperatures of the fluid in the heatexchanger (e.g., heat exchanger 116) in accordance with variousembodiments, as a function of time throughout a complete discharge andrecharge cycle of the phase change material.

For the battery coolant fluid (e.g., fluid in the loop 102):

Q _(BL) =m _(BL) ×C _(P,EG)×(T _(BL,out) −T _(BL,in))   (1)

For the combustion engine coolant fluid (e.g., fluid in the loop 104):

Q _(CE) =h _(CE) ×A _(CE)×(T _(CE,ave) −T _(BL,ave))=m _(CE) ×C_(P,EG)×(T _(CE,in) −T _(CE,out))   (2)

For the phase change material (e.g., phase change material 214, 218)housed in a cylindrical container (e.g., in heat exchanger 116, heatexchanger 1116), heat loss from a cylinder:

$\begin{matrix}\begin{matrix}{Q_{PCM} = {2\pi \; {Lk}_{PCM} \times \left( {T_{c} - T_{w,{i\; n}}} \right)}} \\{= {2\pi \; {Lk}_{W} \times {\left( {T_{W,{i\; n}} - T_{W,{out}}} \right)/{\ln \left( {r_{out}/r_{i\; n}} \right)}}}} \\{= {h_{BL} \times A_{BL} \times \left( {T_{W,{out}} - T_{{BL},{ave}}} \right)}}\end{matrix} & (3)\end{matrix}$

The above-noted rate equations are coupled with an energy equationwritten for the sensible heat change or heat of fusion change for thephase change material over a small time step, Δt:

For sensible heat change:

Q _(PCM) =M _(PCM) ×C _(P,PCM)×(T _(f,PCM) −T _(i,PCM))/Δt   (4a)

For heat change associated with crystallization/melting:

Q _(PCM) =[M _(PCM)×ΔH−M_(PCM) ×C _(P,PCM)×(T _(melt) −T _(c))]/Δt  (4b)

where A_(BL)=heat transfer area at the battery fluid (e.g., fluid in theloop 102) and phase change material container (e.g., heat exchanger 116,heat exchanger 11 16) interface

A_(CE)=heat transfer area of combustion engine exchanger

C_(P,EG)=heat capacity of fluid (e.g., in the loop 102) coolant(ethylene glycol)

C_(P,PCM)=heat capacity of the phase change material

ΔH=heat of fusion for the phase change material

Δt=time step

h_(BL)=convective heat transfer coefficient for the battery coolantfluid at the exterior wall of the phase change material container

h_(CE)=convective heat transfer coefficient for the combustion enginecoolant fluid (e.g., fluid in the loop 104)

k_(PCM)=thermal conductivity of the phase change material

k_(w)=thermal conductivity of the wall material holding the phase changematerial

L=length of cylinder housing the phase change material

M_(PCM)=mass of phase change material

m_(BL)=mass flow rate of battery coolant fluid

m_(CE)=mass flow rate of combustion engine coolant

Q_(BL)=heat transfer rate for the battery coolant

Q_(CE)=heat transfer rate for the combustion engine coolant

Q_(PCM)=heat transfer rate for the phase change material

r_(i), r_(o)=inner, outer radius of cylinder holding the phase changematerial

T_(BL)=temperature of the battery coolant fluid

T_(c)=centerline temperature of phase change material

T_(CE)=temperature of combustion engine coolant fluid

T_(f,PCM)=phase change material temperature at the end of time step

T_(i,PCM)=phase change material temperature at the start of time step

T_(melt)=melting temperature of phase change material

T_(w)=wall temperature of container holding phase change material

Depending on the regime being modeled, the above-described equations maybe solved iteratively for small time steps to provide a temperatureprofile as a function of time.

In a control volume approach, thermal analysis of the battery or batterymodule 110 involves applying the conservation of energy equation (e.g.,first-law analysis) to a control volume having encapsulated battery(e.g., battery 110) identified as “V” in the below equations:

The general equation may be provided as follows:

${\frac{\delta \; Q}{d\; t} - \frac{\delta \; W_{s}}{d\; t}} = {{\int{\int_{cs}{\left( { + \frac{p}{\rho}} \right){\rho \left( {\overset{\_}{v}\; \bullet \; \overset{\_}{n}} \right)}{A}}}} + {\frac{\partial}{\partial t}{\int{\int{\int_{cv}{{\rho}{V}}}}}} + \frac{\delta \; W_{M}}{d\; t} + \left. \frac{\delta \; Q_{source}}{d\; t}\mspace{79mu}\uparrow\mspace{191mu}\uparrow\mspace{371mu}\uparrow \right.}$

where quantities marked by an arrow would have zero or near-zero valuesin some cases.

Thus, for the thermal management system 100 according to variousaspects:

$\begin{matrix}{{\frac{\delta \; Q}{d\; t} = {{\frac{\partial}{\partial t}{\int{\int{\int_{cv}{\; \rho {V}}}}}} + \frac{\delta \; Q_{source}}{d\; t}}}{{{For}\mspace{14mu} {discrete}\mspace{14mu} \Delta \; t},{{\frac{\delta \; Q_{source}}{d\; t} \cong {{\overset{.}{q}}_{source}V\mspace{14mu} {for}\mspace{14mu} {{\overset{.}{q}}_{source}( = )}\frac{Energy}{{Vo}\; l\; {\bullet time}}}}\therefore\left\lbrack {\frac{\delta \; Q}{d\; t} = {{\frac{\partial}{\partial t}{\int{\int{\int_{cv}{\; \rho {V}}}}}} + {{\overset{.}{q}}_{source}V}}} \right\rbrack}}} & (1)\end{matrix}$

In some cases, {dot over (q)}_(source) V is not shown as a separateterm. Following that convention:

$\begin{matrix}\left\lbrack {\frac{\delta \; Q}{d\; t} = {\frac{\partial}{\partial t}{\int{\int{\int_{cv}{{\rho}{V}}}}}}} \right\rbrack & (2)\end{matrix}$

The left hand side (LHS) of Equation (2) shows:

$\frac{\delta \; Q}{d\; t}\text{:}$

The rate of heat addition (or subtraction) to the control volume is dueto both convection from the heat transfer medium and the internal heatsource. Thus, we define

$\begin{matrix}\left\lbrack {\frac{\delta \; Q}{d\; t} = {{h\; {A\left( {T_{\infty} - T} \right)}} + {{\overset{.}{q}}_{source}V}}} \right\rbrack & (3)\end{matrix}$

where h is the heat transfer film coefficient or convection coefficient;A≡heat transfer surface area (encapsulated cylinder wall plus one end).

The right hand side (RHS) of Equation (2) shows:

$\frac{\partial}{\partial t}{\int{\int{\int_{cv}{{\rho}{V}\text{:}}}}}$

The rate of energy increase within the control volume, assuming constantproperties, can be expressed as

$\begin{matrix}{\left\lbrack {{\frac{\partial}{\partial t}{\int{\int{\int_{cv}{{\rho}{V}}}}}} = {\rho \; {Vc}_{p}\frac{T}{t}}} \right\rbrack,} & (4)\end{matrix}$

a thermodynamic-based relation.

Setting RHS's of Eqs. (3) and (4):

$\begin{matrix}{\left\lbrack {{\rho \; {Vc}_{p}\frac{T}{t}} = {{h\; {A\left( {T_{\infty} - T} \right)}} + {{\overset{.}{q}}_{source}V}}} \right\rbrack {or}{\frac{T}{t} = {\frac{1}{\rho \; {Vc}_{p}}\left\lbrack {{h\; A\left( {T_{\infty} - T} \right)} + {{\overset{.}{q}}_{source}V}} \right\rbrack}}} & (5)\end{matrix}$

The above provides three independent equations and three unknowns underthe method based on the lumped-parameter model (LPM).

$\begin{matrix}\left\lbrack {\frac{\Delta \; T}{\Delta \; t} \cong {\left( \frac{1}{\rho \; {Vc}_{p}} \right)_{Batt}\left\lbrack {{{hA}\left( {T_{\infty} - T} \right)} + \underset{\underset{{\overset{.}{q}}_{source}V}{{\uparrow i}.e.}}{{\overset{.}{q}}_{source}(T)}} \right\rbrack}} \right\rbrack & (6)\end{matrix}$

where

-   -   ΔT≡T−T_(o)    -   T is unknown    -   ρ, V, c_(p) for battery

Alternately, the exact analytical solution of Eq (6) in differentialform is

$\left( \frac{{h\; {A\left( {T_{\infty} - T} \right)}} + {{\overset{.}{q}(T)}V}}{{h\; {A\left( {T_{\infty} - T_{o}} \right)}} + {{\overset{.}{q}\left( T_{o} \right)}V}} \right) = ^{- {(\frac{hAt}{\rho \; {Vc}_{p}})}_{Batt}}$

Here, T and T_(∞) are unknown.

$\begin{matrix}{\frac{\Delta \; Q_{cell}}{\Delta \; t} = {{h\; {A\left( {T_{\infty} - T} \right)}} + {{\overset{.}{q}}_{source}V}}} & (7)\end{matrix}$

or, more properly

$\left\lbrack {\frac{\Delta \; Q_{cell}}{\Delta \; t} \cong {{h\; {A\left( {T_{\infty} - T} \right)}} + {{{\overset{.}{q}}_{source}(T)}V}}} \right\rbrack$

Unknowns are (ΔQ, T_(∞),T) .

Regarding heat received by

$\underset{resident}{(M)}\mspace{14mu} {and}\mspace{14mu} \underset{Labile}{\overset{.}{m}}$

coolant in/through battery module (e.g., battery 110), given here on a“per N cells” basis

$\begin{matrix}{{\frac{\Delta \; Q_{cool}}{\Delta \; t} \cong {\left\{ {\overset{.}{m}\; C_{p}\Delta \; T} \right\rbrack \mspace{14mu} {form}}}{{Note}\mspace{14mu} {{that}\mspace{14mu}\left\lbrack {{\Delta \; Q_{cool}} = {N_{cell}\Delta \; Q_{cell}}} \right\rbrack}}} & (8)\end{matrix}$

In the following two expressions, the first applies if C_(p) is f(T);otherwise, the second expression holds.

$\begin{bmatrix}{{\frac{\Delta \; Q_{cool}}{\Delta \; t} = {\left( {{\overset{.}{m}}_{\underset{cool}{Batt}} + \frac{M_{\underset{cool}{Batt}}}{\Delta \; t}} \right)\left( {{{C_{p}\left( T_{\infty} \right)}T_{\infty}} - {{C_{p}\left( T_{\infty}^{o} \right)}T_{\infty}^{o}}} \right)}}} \\{{\frac{\Delta \; Q_{cool}}{\Delta \; t} = {\left( {\overset{.}{m} + \frac{M}{\Delta \; t}} \right){C_{p}\left( {T_{\infty} - T_{\infty}^{o}} \right)}}}}\end{bmatrix}\quad$

Unknowns are (ΔQ_(cell), T_(∞)). T_(∞) ⁰ is initial or inlet coolent Twith respect to Batt.

Since C_(p) for liquids beneath their boiling points is generallyreasonably constant, then the simpler form of Eq. (8) shown above isjustified. However, the source heat term is firmly dependent on T. Thus,the above equations may be summarized as

$\begin{matrix}{\frac{\Delta \; T}{{\Delta \; t}\;} = {\frac{\left( {T - T_{0}} \right)}{\Delta \; t} \cong {\left( \frac{1}{\rho \; {Vc}_{p}} \right)_{Batt}\left\lbrack {{{hA}\left( {T_{\infty} - T} \right)} + {{{\overset{.}{q}}_{source}(T)}V}} \right\rbrack}}} & (9) \\\left\lbrack {\frac{\Delta \; Q_{cell}}{\Delta \; t} \cong {{h\; {A\left( {T_{\infty} - T} \right)}} + {{{\overset{.}{q}}_{source}(T)}V}}} \right\rbrack & (10) \\{\frac{N_{cell}\Delta \; Q_{cell}}{\Delta \; t}\underset{\underset{\underset{{or}\mspace{14mu} {other}\mspace{14mu} {representation}}{\downarrow}}{--{--{--{-- -}}}}}{\cong \left( {\overset{.}{m} + \frac{M}{\Delta \; t}} \right)_{\underset{cool}{Batt}}}{C_{p_{cool}}\left( {T_{\infty} - T_{\infty}^{o}} \right)}} & (11)\end{matrix}$

Since {dot over (q)}_(source) ^((T)) depends on average orrepresentative T over Δt, then solving these equations for the unknowns(T, T_(∞), ΔQ_(cell)) may require an iterative method while checking theBiot (Bi) number to verify applicability of the lumped-parameter model(LPM) for heat transfer.

${{Bi} \equiv \frac{h\; {V/A}}{k}};$

Bi≦0.2 for LPM to be valid.

One such iterative method involves the following elements:

-   1. Estimate T (T_(guess))-   2. Determine {dot over (q)}_(source) ^((T))−(from battery data as    f(T) or Ohmic heating expression)-   3. Solve set of equations for (T, T_(∞), ΔQ_(cell))-   4. Check value of T_(solved) vs T_(guess)-   5. Update Tess and repeat steps 2-4 until determined agreement is    seen between T_(solved) and T_(guess).

Aspects of the invention provide various advantages, which in someembodiments include an option to perform electrical preheating ofvehicles. The thermal management system having the phase change material(e. g., an intelligent-based phase change material) would preheatvehicle components in accordance with preset options (e.g., regionallydefined), thus eliminating the need for a user to connect (e.g., plug)or disconnect (e.g., unplug) an electrical heater before and after eachuse. Effective thermal management of hybrid electrical vehicles (HEVs)increases battery efficiency by maintaining favorable electrolyteconductivity, while extending battery lifetime by avoiding excessivetemperatures. Thus, replacement of the batteries may be foregone untilwell within the expected lifetime of the batteries. Consequently, an HEVhaving the thermal management system in accordance with various aspectswould have greater power at low temperatures.

Additionally, comforts of a passenger cabin of the vehicle may beenhanced by using the thermal management system, in accordance withvarious aspects, during cold-start conditions, as the design of thethermal management system permits excess thermal energy to be directedto the cabin heater core (e.g., internal combustion engine cabin 1 18)as determined by control logic protocol described above.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A thermal management method for a vehicle, comprising: providing aheat exchanger having a thermal energy storage material disposedtherein; providing first and second coolant loops configured tocirculate distinct coolant mixtures through the respective first andsecond coolant loops; thermally coupling the first coolant loop to abattery module located within the first coolant loop; thermally couplingthe second coolant loop to the heat exchanger; providing an interface inclose proximity to the second coolant loop, wherein the interface isconfigured to transfer heat generated by an internal combustion engineof the vehicle to the heat exchanger, via the second coolant loop, forstorage within the thermal energy storage material; and selectivelyperforming one or more of preheating the battery module, heating apassenger cabin of the vehicle, increasing sensible heat or latent heatof fusion of the material from a first thermal state to a higher secondthermal state using the heat stored within the thermal energy storagematerial.
 2. The method of claim 1, further comprising: thermallycoupling a second heat exchanger to the first coolant loop to cool thebattery module; and providing a bypass fluid path to deliver the firstcoolant mixture to the second heat exchanger bypassing the heatexchanger in order to cool the battery module by reducing a temperatureT_(Batt) of the battery module below a maximum desirable temperatureT_(max).
 3. The method of claim 2, further comprising: transferring theheat generated by the internal combustion engine to the heat exchangervia the second fluid loop for storage in the heat exchanger; andselectively delivering the heat stored in the heat exchanger to thebattery module via the first fluid loop to increase the temperatureT_(Batt) of the battery module.
 4. The method of claim 3, furthercomprising: transferring the heat generated by the internal combustionengine to the heat exchanger; and after receiving the heat at the heatexchanger, one or more of sensible heat or latent heat of fusion of thephase change material is increased from a first thermal state to ahigher different thermal state.
 5. The method of claim 4, furthercomprising selectively delivering the heat generated by the internalcombustion engine to heat a passenger cabin of the vehicle.